Background: Spinal muscular atrophy (SMA) is a congenital motor neuron disease leading to progressive muscle weakness, disability, and in most severe cases without treatment, infantile death. While most studies focus on motor function, evaluating cognitive function in patients with SMA via validated instruments could elucidate SMA pathology and treatment effects.
Objective: We sought to identify and evaluate instruments used to assess cognitive function in children and adolescents with SMA.
Methods: We conducted a literature review of English-language original research publications in EMBASE and PubMed with the following criteria: patients with SMA types 1, 2 or 3; cognitive function assessed; no study design/time period restrictions. A structured data abstraction form included name of instrument, version, applicable age group, SMA type, content/domains, and findings.
Results: Of 1,549 unique records initially screened, 37 relevant papers and 28 instruments were identified. Commonly used instruments included the Wechsler Intelligence Scale (n=12 studies), Bayley Scales of Infant and Toddler Development (n=6), Child Behavior Checklist (n=5), as well as eye tracking devices, Pediatric Quality of Life Inventory, and Raven text (n=4 each). The domains assessed most often were language abilities (n=10) and memory (n=5). The majority of studies indicated that patients with SMA type 1 had impaired cognition measured using different tools with different endpoints. However, these studies did not compare findings for other SMA types, instruments were not consistently applied, and each instrument included domains unrelated to cognition as well.
Conclusions: Assessment of cognition in the first years of life, when the neural foundations of cognition are forming, is inherently challenging. While available instruments include domains related to cognitive function, no particular validated instrument is optimal for assessing cognition in patients with SMA. Development and validation of a new instrument for cognitive assessment tailored for patients with SMA may help address this unmet need.